[OMCSession] improve log messages for model simulation using OM executable

* use check=False => no CalledProcessError exception; possibility to
  handle the error code
* error code needs to be checked (compare == 0) by the caller!
* improve log messages; print returncode if it is != 0 with stdout

Author: syntron

OMPython/OMCSession.py

@@ -800,20 +800,23 @@ def run_model_executable(cmd_run_data: OMCSessionRunData) -> int:
                 env=my_env,
                 cwd=cmd_run_data.cmd_cwd_local,
                 timeout=cmd_run_data.cmd_timeout,
-                check=True,
+                check=False,
             )
             stdout = cmdres.stdout.strip()
             stderr = cmdres.stderr.strip()
             returncode = cmdres.returncode
 
-            logger.debug("OM output for command %s:\n%s", repr(cmdl), stdout)
+            if returncode != 0:
+                logger.warning("OM executable run %s with returncode=%d and stdout:\n%s",
+                               repr(cmdl), returncode, stdout)
+            else:
+                logger.debug("OM executable run %s with stdout:\n%s", repr(cmdl), stdout)
 
             if stderr:
                 raise OMCSessionException(f"Error running model executable {repr(cmdl)}: {stderr}")
+
         except subprocess.TimeoutExpired as ex:
             raise OMCSessionException(f"Timeout running model executable {repr(cmdl)}") from ex
-        except subprocess.CalledProcessError as ex:
-            raise OMCSessionException(f"Error running model executable {repr(cmdl)}") from ex
 
         return returncode